AstraZeneca and Daiichi Sankyo’s Datroway has become the first cancer drug to show an overall survival benefit against chemotherapy for certain patients with a particularly aggressive form of breast cancer.
In a phase 3 trial, the antibody-drug conjugate (ADC) has scored as a first-line treatment for those with locally recurrent inoperable or metastatic triple-negative breast cancer (TNBC) for whom immunotherapy is not an option.
Datroway achieved its dual primary endpoints, showing statistically significant and clinically meaningful improvements in overall survival (OS) and progression-free survival (PFS) compared to chemotherapy.
“We expect today’s results will mark an inflection point in the treatment of these patients who have the poorest prognosis of any type of breast cancer and urgently need better options,” Susan Galbraith, AZ’s head of oncology and hematology R&D, said in a release.
The “landmark” results could pave the way for Datroway to become a treatment option for the 70% of those with TNBC who are not eligible for immunotherapy, Daiichi R&D chief Ken Takeshita added in the release. Chemotherapy remains the standard of care for these patients.
The companies plan to share data from the TROPION-Breast02 trial with regulators around the world with hopes of “bringing Datroway to patients with triple-negative breast cancer as soon as possible," Takeshita added.
TNBC, which is diagnosed more frequently in younger women and more often in those who are Black or Hispanic, accounts for 15% of cases of breast cancer, the companies said. The median overall survival rate of those with TNBC is 12 to 18 months, with just 14% of patients living five years after they have been diagnosed.
In three other phase 3 studies, the companies are investigating Datroway in combination with AZ’s PD-L1 blockbuster Imfinzi across three other stages and treatment settings of TNBC.
The results continue the upward trajectory of Datroway, which gained its first FDA approval in January of this year for those with previously treated metastatic, HR-positive, HER2-negative breast cancer. Five months later, the FDA tacked on a label expansion for the medicine to treat patients with locally advanced or metastatic epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC).
Datroway targets the TROP2 protein found on the surface of tumor cells in many cancer types. AZ was so convinced of the potential of Datroway in 2020 that it paid Daiichi $1 billion upfront for the collaboration, with an additional $5 billion tied to potential regulatory and sales milestones. AZ has pegged the drug's annual peak sales potential at $5 billion.
In November of last year, the companies pulled an FDA filing for Datroway in second-line nonsquamous NSCLC after a phase 3 study showed mixed results.
Datroway is the second antibody-drug conjugate from the partner companies, following blockbuster Enhertu, which has been on the market for six years and generated sales of $3.75 billion in 2024.